Floral advertisement scent in a changing plant-pollinators market

Plant-pollinator systems may be considered as biological markets in which pollinators choose between different flowers that advertise their nectar/pollen rewards. Although expected to play a major role in structuring plant-pollinator interactions, community-wide patterns of flower scent signals remain largely unexplored. Here we show for the first time that scent advertisement is higher in plant species that bloom early in the flowering period when pollinators are scarce relative to flowers than in species blooming later in the season when there is a surplus of pollinators relative to flowers. We also show that less abundant flowering species that may compete with dominant species for pollinator visitation early in the flowering period emit much higher proportions of the generalist attractant β-ocimene. Overall, we provide a first community-wide description of the key role of seasonal dynamics of plant-specific flower scent emissions, and reveal the coexistence of contrasting plant signaling strategies in a plant-pollinator market

Lack of trade-offs between the male and female sexual functions in the gynodioecious herb Geranium sylvaticum

Resource allocation trade-offs between sexual functions are predicted, but these are usually measured only at the whole plant level. In some gynodioecious species, individuals with partially restored male fertility exist providing an opportunity to investigate whether the costs associated with male fertility restoration are linked to seed production. In this study, we examined whether there is a relationship between the numbers of stamens and seeds produced both at the flower level and at the plant level in the gynodioecious herb Geranium sylvaticum. We individually marked flowers in plants varying in the degree of male sterility in the field and counted the number of seeds produced. There was no significant correlation between the numbers of stamens and seeds produced at the flower level suggesting an absence of resource trade-off between female and male functions. Furthermore, the numbers of stamens and seeds were positively correlated at the plant level. The lack of trade-offs between the two sexual functions in this species indicates that relative sex allocation was not affected by resources within a single season and/or that the male costs were relatively small

Géographie historique du monde méditerranéen

Voici rassemblés les premiers résultats encore partiels d'une vaste enquête lancée avec l'aide de la Fondation Européenne de la Science sur le territoire byzantin, notamment le monde littoral. Enquête multiple sur des régions variées (de la Sicile au Proche-Orient), des époques différentes (ive-xive siècles), des sources diverses (topographie, architecture, archives, voyageurs), les documents sont là de première main. Leur déchiffrage ne fait que commencer mais il bousculera, grâce au croisement des regards, beaucoup d'idées reçues. Leur moindre mérite ne sera pas la mise en lumière du rôle de Byzance en Méditerranée orientale et dans les Balkans. Byzance, ou l'autre façon de comprendre l'Europe orientale et les pays arabes